Conventional actuators (actuating drives) that include an electronically commutated motor are connected via a transmission to the actual actuating element, in particular an actuator lever.
For the operation of these actuators, it is important to know a position of the rotor of the commutated motor and an absolute position of the actuator lever.
This can be achieved through the direct acquisition of the absolute position of the actuator lever and of the rotor using two sensors.
If only one sensor is used, this sensor can acquire either the absolute position of the actuator lever or the absolute position of the rotor. In the first case, the absolute position of the rotor can be determined as a function of a gear ratio of the transmission. In the second case, the absolute position of the actuator lever can be determined as a function of the transmission gear ratio.
In order to produce high torques at the actuator lever using electronically commutated motors having a low torque, a plurality of transmission stages are connected in series in order to produce a high transmission gear ratio. Due to the play in the transmission, at these high transmission gear ratios there occur high degrees of imprecision in the determination of the absolute position using only one sensor. If one of the gears can completely rotate more than once during a rotation of another gear, an unambiguous assignment of the absolute positions is not possible.
Therefore, in conventional sensor referencing with one sensor, during a reference trip the sensor acquires the absolute position of the rotor and determines the absolute position of the actuator lever by arriving at a mechanically characteristic point, e.g. a stop, and acquiring the relative movement beginning from this point. This is a reliable and precise method for determining the absolute position of the actuator lever.
However, this is time-intensive.
Therefore, it is desirable to provide an absolute position determination using one sensor that is improved in comparison therewith.